Topband: more strange signals

[Lee K7TJR]

The 160 band was as quiet this morning as I can ever recall in the Ja/Ua0 direction. I ran across a series of stations at 1818.15, 1814.5,1813.25, and 1811.6.  These were not the usual fishing beacons as I have heard many of those before. These signals were series of three dots from each frequency repeated at 1 second intervals and each dot sounded as though it may have been a different transmitter or location. The dots were very precisely timed and each different frequency repeated the same type of signal. I suspect these may be something similar to the ZL digi for GPS type location correction and my best guess is they are originating in UA. Any one know what they may be?
Lee K7TJR Oregon